It's a positive sign that he's admitted he has a problem and wants help but he is going to have to agree to some pretty stringent stuff IME.
My husband has racked up tens of thousands in debt twice over despite being bailed out the first time and being on course with repayments. He has fucked our lives with it. Despite this I am supporting him as he has no-one else and it's been part of an ongoing breakdown related to finding out our dd was abused and the family fallout from that. This is how I can square the monumental lies, deceit and general shit this horrendous thing has caused but he is under no illusions that I will walk if I ever find he has even looked sideways at one of those bastard machines ever again.
I have taken all control of finances and ditched all but one joint account which I monitor daily. The house and all savings are in my name. He has self-excluded from bookies although TBH that's not foolproof by any means. So, so many of the fucking places absolutely everywhere
. I have k9 installed on the computer which is a free blocker. There are other gambling blockers but you have to pay for them. He goes to GA weekly and has had Gamcare counselling (not completed the course due to temp work and job hunting commitments) which he found very useful.
He carries little to no cash and when he does I see what he's bought or the receipts. I also have access to his credit report (Noddle is free for life) which show loans, credit cards and bank accounts along with his banking although he got round that this time by changing logins and spinning me a line about how he was sorting it so be ready for that one if he agrees. It cost me dear to believe those lies.
If your dh is using his phone to gamble he could consider changing it for a basic PAYG as from what I gather it might not be possible to install blockers on a phone.
My husband was suicidal over what he has done in the summer. AFAIK he hasn't gambled for getting on for 18 weeks now and I am cautiously hopeful that this is it but I do not intend to relax my guard for an instant. He knows I will never trust him with money again.
You already know how devious this addiction makes a gambler. If your husband is truly ready to kick this into touch he should be willing to agree to do whatever it takes but you need to be aware that there is nothing you can do to make him change. He absolutely has to want that for himself.
Your absolute priority must be to protect yourself financially right now and you must insist on complete honesty and openness as to the true position now and ongoing.
Sorry to be so doom and gloom but this is my reality. It totally sucks but I want to give him the chance to be the brilliant person he was before this madness took over and I hope and believe it can be done.